Practise with fresh pairs from your chosen category. Each round gives you a known measurement to use as a reference.
Choose the length
Play 5, 10 or 20 rounds, or choose endless mode and finish after at least five rounds. Practice results stay separate from Daily. Compare totals from games of the same length.
Adjust your estimate
Drag one finger or pinch with two fingers to resize the white silhouette. The ruler and +/− buttons also adjust your estimate. The zoom buttons change the view. Scroll outside the board to read the page.
Learn from the answer
Read the measurement label: height, length and wingspan are different dimensions. After each round, compare your estimate with the recorded size. New games use active library entries; retired entries are excluded.
Invite a friend
After a game, create a challenge link so a friend can play the same questions without registering. Preview the format before sharing: a result image may reveal answers.